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Fishing spiders

Far from their natural habitat, spiders of the genus Dolomedes are sometimes found in swimming pools, but they rarely stay.

Photo: Insectarium de Montréal (Claude Pilon)

Dolomedes tenebrosus, North America (Mounting specimens).

Photo: Insectarium de Montréal (René Limoges)

In Quebec, spawning takes place in the summer or spring. Spiderlings molt several times before the first winter, then again a few times during the second summer. They reach the adult stage after a second winter rest.

Photo: Insectarium de Montréal (René Limoges)

The dolomedes feed on small insects, aquatic or other, and sometimes large dragonflies. They can also eat tadpoles and small fish. They hunt their prey on the ground, in vegetation, underwater and on the water's surface.

Photo: Insectarium de Montréal (Gilles Murray)

Tabs group

Description

Fishing spiders belong to the Pisauridae family and the Dolomedes genus. There are about 100 species in the world and a dozen species in North America, excluding Mexico. In Quebec, there are four species, all semi-aquatic: Dolomedes scriptus, Dolomedes tenebrosus, Dolomedes triton and Dolomedes striatus.

These spiders often attract attention because they are so large. The body of certain specimens, not counting their legs, can grow as long as 2.8 cm! Depending on species, their colouring varies from greyish brown to greenish brown. Females are generally larger than males.

After mating, the female spins a spherical silk cocoon in which she lays her eggs. She watches over it and carries it around with her, even on the water, until the eggs hatch. Before the spiderlings hatch, the female places the cocoon in leaves and spins a protective web shaped like a tent or a bell around it that serves as a nursery. The female protects the cocoon until spiderlings hatch. Once hatched, the spiderlings disperse.

French name

Dolomèdes

English name

Fishing spider

Class

Arachnida

Order

Araneae

Habitat/Diet

Habitat

Fishing spiders generally live near the water, preferably on the shores of lakes, ponds and other bodies of water. They are frequently seen on stones, docks and boats. However, Dolomedes tenebrosus is often found in the forest, far from aquatic habitats, and is sometimes found in houses and other buildings.

Did you know?

Interesting facts

Fishing spiders do not attack humans, whether on the ground or in the water. They flee when they are frightened. There are a few cases of bites, painful but not serious, all related to people handling the spiders. They should not be handled with bare hands.

Once they reach adulthood, fishing spiders die at the end of the summer after they reproduce.

Your dock may be full of places where fishing spiders and other spiders can hide. You should change or repair your dock to eliminate their hiding places if you want there to be fewer of them.

The best solution is undoubtedly to learn to live with these spiders, because their presence is a sign that the shores of your lake and your living environment are in good health.

Ecological roles

These spiders are useful. They eat insects and aquatic invertebrates. When they hunt in the water, they are sometimes eaten by fish. They are also food for animals and birds.